Re: dts and dtsi files on which I tested the syntax for my recent patch set.

[David Gibson <david-xT8FGy+AXnRB3Ne2BGzF6laj5H9X9Tb+@public.gmane.org>]

On Wed, Oct 20, 2010 at 07:08:36PM -0700, John Bonesio wrote:
> On Wed, 2010-10-20 at 17:46 -0600, Grant Likely wrote:
> > On Wed, Oct 20, 2010 at 03:22:17PM -0700, John Bonesio wrote:
> > > Hi,
> > > 
> > > I have attached the two file I've used to test the new syntax from my
> > > patch set. These might help get a feel for how the syntax and the
> > > features work.
> > 
> > heh, what you should actually do (because you have to anyway) is add
> > testcases for the new features to dtc in the tests directory.  'make
> > check' runs the test cases.
> > 
> > > /remove-node/ &{soc/serial@2400};                  /* an example of using a label rooted path */
> > 
> > As previously mentioned by David, this conflicts with the already
> > established convention of a path that does not start with a '/' means
> > use a value from the /aliases node.  That ambiguity needs to
> > be avoided, so the syntax still needs some massaging.
> 
> I think we should explore this a bit further. I just don't see in the
> lexer code where it would parse anything with the syntax
> &{alias/node/path} (except for my recent patch).
> 
> I looked through the parser too, and it wasn't obvious where it would
> match '&' directly.
> 
> Maybe I'm just missing it.

No, we just weren't being clear.  dtc does not itself expand aliases
in this way.  However, it's a common convention in existing device
tree stuff.  The OF interface will expand aliases in this way, as will
fdt_path_offset().

So it's not an actual ambiguity with existing syntax, but the fact
that your proposed syntax is subtley different from a common existing
device tree convention would violate least-surprise.

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
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